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[70.27.3.10]) by smtp.gmail.com with ESMTPSA id dm52-20020a05620a1d7400b006a6ab259261sm9120434qkb.29.2022.08.01.15.25.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 01 Aug 2022 15:25:41 -0700 (PDT) Date: Mon, 1 Aug 2022 18:25:40 -0400 From: Peter Xu To: "Huang, Ying" Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrea Arcangeli , Andrew Morton , "Kirill A . Shutemov" , Nadav Amit , Hugh Dickins , David Hildenbrand , Vlastimil Babka , Andi Kleen Subject: Re: [PATCH RFC 0/4] mm: Remember young bit for migration entries Message-ID: References: <20220729014041.21292-1-peterx@redhat.com> <87pmhkjzo7.fsf@yhuang6-desk2.ccr.corp.intel.com> MIME-Version: 1.0 In-Reply-To: <87pmhkjzo7.fsf@yhuang6-desk2.ccr.corp.intel.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline ARC-Authentication-Results: i=1; imf22.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=RrGio6Ti; spf=pass (imf22.hostedemail.com: domain of peterx@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=peterx@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1659392744; a=rsa-sha256; cv=none; b=GP9+ujOejNZdv1FcJhI+muFVosGHa0p8metwrprKkew9dHvv0jAy71K80z+0h3PG0Qu10r t20OEL1cmgEAdzrZa48ODz9AkprhvEQAi9X4GlMGsRy1FCjDJYc9bUNsDiAJ+TQfPkAFmQ MpXLXMm1/DRW0db3L076NgOACoLJ/bg= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1659392744; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=JuDYx7rY0J8nhH7yYroLa1iYucx7uxXCdAdFRarEXz8=; b=mU+NXb/Y0C97DMS4IpV/yknfNSWLugl1/OWDrQlZ7Bgh7Y+m1P65njClqU/AQSDLbaVolx 0lsHMBDEeZnSti9fx3IAz5LYj00U7XE2ILt32AunK1jyFomM1LHacB1O53gJ4GCj1nzrWj qQ/lmSvbRWKYedw38nUU0DoXl6bHqDw= X-Stat-Signature: ntu3rqbqmuduae4bykm9d5f1bstcfaqk X-Rspamd-Queue-Id: 60C6DC00D0 X-Rspam-User: Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=RrGio6Ti; spf=pass (imf22.hostedemail.com: domain of peterx@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=peterx@redhat.com; dmarc=pass (policy=none) header.from=redhat.com X-Rspamd-Server: rspam04 X-HE-Tag: 1659392744-314021 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Aug 01, 2022 at 01:33:28PM +0800, Huang, Ying wrote: > If my understanding were correct, max_swapfile_size() provides a > mechanism to identify the available bits with swp_entry_t and swap PTE > considered. We may take advantage of that? That's an interesting trick, I'll have a closer look, thanks for the pointer! > > And according to commit 377eeaa8e11f ("x86/speculation/l1tf: Limit swap > file size to MAX_PA/2"), the highest bit of swap offset needs to be 0 if > L1TF mitigation is enabled. > > Cced Andi for confirmation. Yeah it'll be great to have a confirmation, hopefully max_swapfile_size() should have covered that case. -- Peter Xu